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public interface Substitution
A Substitution maps a set of Variables to a set of Terms.
Method Summary  

boolean 
contains(Variable var)
This function tests whether this Substitution contains the given Variable. 
Term 
getValue(Variable aVar)
This function returns the Term the given Variable is mapped to under this Substitution. 
boolean 
unify(Term lTerm,
Variable rVar)
This function attempts to extend this Substitution such that the given Variable (from the "right" expression) and the given Term (from the "left") are unified and returns whether this succeeded. 
boolean 
unify(Variable lVar,
Term rTerm)
This function attempts to extend this Substitution such that the given Variable (from the "left" expression) and the given Term (from the "right") are unified and returns whether this succeeded. 
boolean 
unify(Variable lVar,
Variable rVar)
This function attempts to extend this Substitution such that the given Variables will be unified and returns true if this was possible. 
Method Detail 

boolean unify(Variable lVar, Term rTerm)
This function attempts to extend this Substitution such that the given Variable (from the "left" expression) and the given Term (from the "right") are unified and returns whether this succeeded. The given Term must not be a Variable.
lVar
 the Variable the given Term is to be unified withrTerm
 the Term the given Variable will be mapped to
boolean unify(Term lTerm, Variable rVar)
This function attempts to extend this Substitution such that the given Variable (from the "right" expression) and the given Term (from the "left") are unified and returns whether this succeeded. The given Term must not be a Variable.
lTerm
 the Term the given Variable will be mapped torVar
 the Variable the given Term is to be unified with
boolean unify(Variable lVar, Variable rVar)
This function attempts to extend this Substitution such that the given Variables will be unified and returns true if this was possible. Where this matters, the first variable is considered to come from the "left" expression and the second from the "right".
lVar
 a Variable to be associated with the other given VariablerVar
 a Variable to be associated with the other given Variable
boolean contains(Variable var)
This function tests whether this Substitution contains the given Variable. In general, this will be the case if the Variable has been unified with another Variable or a Term.
var
 the Variable that may occur in this Substitution
Term getValue(Variable aVar)
This function returns the Term the given Variable is mapped to under this Substitution. More specifically, if the Variable has been unified with a Constant or FunctionTerm, this function returns that Term instantiated (cloned) under this Substitution. If the Variable is contained in this Substitution but not mapped to a Term (it may have been unified with another Variable only) or the Variable is not contained in this Substitution, then this substitution will be extended to map the given Variable to a new Variable that will also be returned. However, not all implementations can be extended in this way, and an Exception will be thrown if this is not possible.
aVar
 the Variable the mapped Term is being sought for


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